1. Field of the Invention
The present invention relates generally to a cleaning machine and, more specifically, to a dishwashing apparatus and method of use that utilizes a mixture of liquid and granules to clean soiled articles, and includes one or more granule collectors to separate the mixture.
2. Description of Related Art
Dishwashing machines, needed to handle high volume and heavily soiled articles, such as in a commercial setting, are well known in the art. It is common practice to mix small, hard particles, such as granules, with water and detergent to achieve an optimal cleaning mixture that is sprayed under high pressure against articles to be washed. Generally, the machines are equipped with a tank, spraying nozzles, and pumps. The liquid or liquid/granule combination is pumped to the nozzles where it is sprayed against articles to be cleaned. After the articles are cleaned, a separation cycle is necessary in order to remove any leftover residue or granules. Thus, a separation method for the granules is essential.
Many prior art references include machines functioning similarly to the above-described process, utilizing various separation methods. For example, U.S. Pat. No. 4,374,443 to Mosell discloses a cleaning machine that uses a liquid-permeable compartment or cassette which either separates or combines the cleaning liquid and granules. This liquid permeable compartment is located inside a liquid container and connects the bottom of a treatment chamber to the liquid container. The liquid permeable compartment communicates with a pump via a valve-controlled opening. Based upon whether the valve-controlled opening is open or closed, either cleaning liquid alone or a slurry of liquid and granules will be drawn by the pump through a suction chamber which is connected to the liquid container. Once the pump has drawn the liquid or the liquid/granule slurry, the fluid alone or slurry will be sprayed through nozzles located in the treatment chamber against goods to be cleaned. In another patent issued to Mosell (U.S. Pat. No. 4,801,333), a cleaning machine is disclosed that separates granules by using two different levels for liquid and granules. A branch conduit is connected to a bottom outlet and a tank at a position above the surface of a bottom layer of granules below a liquid surface (the granules have a higher density than the liquid). The branch conduit has a float valve at an opening inside the tank and a closure valve between the bottom outlet and the position where the two conduits meet. When the closure valve is opened, the pump will draw from the tank through the bottom conduit, drawing liquid and granules to blast the soiled articles in a treatment chamber. When the closure valve is closed, the pump will draw liquid from the tank through the branch conduit and liquid only will be supplied for rinsing the cleaned articles..
U.S. Pat. No. 5,468,175 to Nilen discloses another way of separating granules in a cleaning machine. The granules are separated by a dividing wall with a pivoting portion at the wall base. The dividing wall separates the tank into two chambers, one with liquid only and the other with liquid and granules. The pivoting arm seals against the tank to prevent granules from passing when closed, and when opened allows granules to pass along with the liquid into the pump, to be recirculated through the system. A different type of separation system was also disclosed by Nilen in U.S. Pat. No. 5,601,480. In this design, separation of granules is done by a separation plate that extends some distance up from the bottom. This separates the tank into two chambers, a small, liquid only chamber and a larger liquid and granule chamber. A second perforated plate may also be attached to the top of the liquid chamber to insure that no granules pass through. Two pumps are required for this system, one connected to each chamber. Depending on the desired make-up of the substance to be sprayed (liquid only or a liquid/granule mixture), each pump is turned on independently.
In U.S. Pat. No. 5,667,431 to Mortin, yet another type of separation device is disclosed. The separation in this patent is done by separating the holding tank into two sections. The first section has a strainer at the bottom that allows the granules to pass into a conduit which is attached to a pump. If water gets too high in the first section it will spill over to the other section. Because the density of the granules is greater than the density of water, the overflow will theoretically contain liquid only. This second, liquid only section also has a conduit which is attached to a pump. Both pumps carry the liquid or liquid/granule mixture to a nozzle arrangement where they are sprayed against the articles to be cleaned. Alternatively, if the density of the granules is less than the water, a separate embodiment contemplates a system where the passage is at the bottom of the tank and the supply means is located in the upper portion.
Finally, U.S. Pat. No. 5,735,730 to Jonemo et al. discloses a dishwasher that uses a valve separation device to separate the granules from the liquid. The granule valve has a socket open at each end, and is associated with a bottom outlet. The socket is guided for vertical displacement between the upper position, with an opening at the lower end of the socket for drawing liquid with granules entrained therein by a pump from a treatment space at a lower level, and a lower position with the opening at the lower end of the socket closed for drawing liquid only by the pump from a higher level at the upper end of the socket. A projecting circumferential flange is provided on the socket below the upper end of the socket forming together with a cap that is located over the socket, a seal for preventing granules from being withdrawn along with the liquid.
While the prior art cleaning machines separate granules from liquids in a variety of ways, all are very difficult to clean at the end of a working shift. This can be largely attributed to the fact that the granules remain in the tank after the cleaning cycle, gravitating around the separation devices. Thus, cleaning the bottom of the tank becomes laborious. In view of the increasing demands from users for improved hygienic properties in the cleaning machines, a need exists to develop a cleaning machine which will collect the granules in an efficient manner so they can be removed for cleaning of the machine. In addition, removal of the granules is advantageous because the amount of granules can be monitored so that granules can be added when necessary to ensure that articles are consistently subjected to optimal cleaning conditions.
It is therefore an object of this invention to provide a granule dishwashing apparatus that is easy to clean at the end of a wash cycle.
It is another object of this invention to provide a granule dishwashing apparatus that utilizes granule collectors to separate granules from liquid.
It is still a further object of this invention to provide granule collectors in a granule dishwashing apparatus that are easy to install and remove.
It is yet another object of this invention to provide a granule dishwashing apparatus that is easy to use and inexpensive to produce.